每隔几秒更新一次 MVC 2 视图

Question

我正在使用 MVC 2，我有一个视图，它只显示带有当前时间的标签。

我想每 5 秒更新一次这个视图（标签），这样时间就会更新。我正在使用下面（取自此处），但是似乎不起作用。

public ActionResult Time()
    {
        var waitHandle = new AutoResetEvent(false);
        ThreadPool.RegisterWaitForSingleObject(
            waitHandle,
            // Method to execute
            (state, timeout) =>
            {
                // TODO: implement the functionality you want to be executed
                // on every 5 seconds here
                // Important Remark: This method runs on a worker thread drawn 
                // from the thread pool which is also used to service requests
                // so make sure that this method returns as fast as possible or
                // you will be jeopardizing worker threads which could be catastrophic 
                // in a web application. Make sure you don't sleep here and if you were
                // to perform some I/O intensive operation make sure you use asynchronous
                // API and IO completion ports for increased scalability
                ViewData["Time"] = "Current time is: " + DateTime.Now.ToLongTimeString();
            },
            // optional state object to pass to the method
            null,
            // Execute the method after 5 seconds
            TimeSpan.FromSeconds(5),
            // Set this to false to execute it repeatedly every 5 seconds
            false
        );

        return View();
    }

提前感谢您的帮助！

Answer 1

您所做的将不起作用，因为一旦将初始响应发送到客户端，客户端将不再侦听来自服务器的该请求的数据。您想要做的是让客户端每 5 秒发起一个新请求，然后简单地返回每个请求的数据。一种方法是使用刷新标头。

public ActionResult Time()
{
    this.HttpContext.Response.AddHeader( "refresh", "5; url=" + Url.Action("time") );

    return View();
}

Answer 2

您需要将重复循环放在客户端，以便它每五秒重新加载一次页面。

一种方法是使用 Javascript：

<script>setTimeout("window.location.reload();",5000);</script>

Answer 3

您提供的代码在服务器上运行，当页面（在本例中为视图）发送到客户端时，服务器会忘记它！您应该创建一个客户端代码，用于每 5 秒刷新一次页面。您可以使用 header 命令（refresh）或脚本：

<script>
    setTimeout("window.location.reload();", /* time you want to refresh in milliseconds */ 5000);
</script>

但如果您只是想刷新页面以更新Time，我永远不会建议您彻底刷新页面。相反，您可以创建一个 JavaScript 函数，每 5 秒计时一次，并计算当前时间并更新标签。